opening davinci resolve 15

I have downloaded the free version of resolve 15 as a trial before purchasing the full version. However, when I try to open the program I get two screens. The first says starting up then a few seconds later the screen changes to say looking for control system. After a few seconds the screen disappears and the program closes with the resolve icon removed from the dock.
My Mac is using MacOS High Sierra version 10.13.4.
Am I missing something from the program?